Police could be seen rushing to help their colleague as the terrorist Khalid Masood is also treated

PA Graphics

Police have appealed for more information after the Wednesday attacks

PA

PC Keith Palmer who was stabbed to death outside Parliament

Staci Martin

Keith Palmer posed in a photograph with US tourist Staci barely 45 minutes before the attack

Maniac behind London terror attack in Westminster named as Khalid Masood

Theresa May praises MP Tobias Ellwood who tried to save PC Keith Palmer after London terror attack on Westminster

Two more "significant" arrests have been made in connection to the attack, with police swooping on the West Midlands and north west.

New Scotland Yard Deputy Acting Commissioner Mark Rowley said that officers were involved in a "large, fast-paced" investigation.

He said: "Our investigation focuses on understanding his motivation, preparation and his associates.

"Whilst there is no evidence of further threats you will understand our determination to find out if he either: acted totally alone inspired by terrorist propaganda or, if others have encouraged, supported or directed him."